Efficient Removal Of Organic Dyes Research Articles

Magnetic Mesoporous Silica Nanoparticles Functionalized with 5,5′-Dithiobis(2-Nitrobenzoic Acid) for Highly Efficient Removal of Organic Dyes from Contaminated Water

The removal of organic pollutants has become an increasingly important environmental concern. In recent years, there has been significant research into the use of nanomaterials for removing organic dyes in single-component systems. In this study, magnetic mesoporous silica nanoparticles (magnetic MSNs) were prepared with an average particle size of 170 nm. Iron oxide nanoparticles (20 nm) were embedded within the mesoporous silica structure. These nanoparticles were functionalized with amine, derivatized with thiol, and then reacted with 5,5′-dithiobis-(2-nitrobenzoic acid) (DTNB). The presence of DTNB molecules attached to the surface was confirmed by FTIR spectra, as evidenced by the appearance of peaks at ∼1528 cm−1 and ∼1365 cm−1. The nanoadsorbents demonstrated high removal efficiency for bromothymol blue (BT) and methyl orange (MO) at a pH below 5, with a maximum adsorption capacity of 139.27 mg/g and 101.62 mg/g for BT and MO, respectively. The linear regression coefficient value suggested that the adsorption of BT and MO onto magnetic MSNs-DTNB followed the Langmuir isotherm and second-order process. Overall, these findings suggest that magnetic MSNs-DTNB could be a promising nanoadsorbent for removing organic pollutants from contaminated water sources.

β-Cyclodextrin network crosslinked by novel phosphonium-based tetrakiscarboxylic acid derived from PH3 tail gas: Synthesis and application for rapid removal of organic dyes from wastewater

Organic dyes, such as methyl orange (MO), Congo red (CR), crystal violet (CV) and methylene blue (MB), are common organic pollutants existing in wastewater. Therefore, the exploration of bio-based adsorbents for the efficient removal of organic dyes from wastewater has gained many attentions. Here, we report a PCl3-free synthetic method for the synthesis of phosphonium-containing polymers, in which the prepared tetrakis(2-carboxyethyl) phosphonium chloride-crosslinked β-cyclodextrin (TCPC-β-CD) polymers were applied to the removal of dyes from water. The effects of contact time, pH (1−11), and dye concentration were investigated. The selected dye molecules could be captured by the host-gest inclusion of β-CD cavities, and the phosphonium and carboxyl groups in the polymer structure would respectively facilitate the removal of cationic dyes (MB and CV) and anionic dyes (MO and CR) via electrostatic interactions. In a mono-component system, over 99 % of MB could be removed from water within the first 10 min. Based on the Langmuir model, the calculated maximum adsorption capacities of MO, CR, MB, and CV were 180.43, 426.34, 306.57, and 470.11 mg/g (or 0.55, 0.61, 0.96 and 1.15 mmol/g), respectively. Additionally, TCPC-β-CD was easily regenerated using 1 % HCl in ethanol, and the regenerative adsorbent still showed high removal capacities for MO, CR, and MB even after seven treatment cycles.

CoNi–MOF–Graphene Magnetic Nanocomposites for the Electrocatalytic Detection of Glucose and the Efficient Removal of Organic Dyes

The design of a nanocomposite with electrocatalytic activity and recyclable development for the detection of small biomolecules and the removal of environmental pollutants has received enormous attention. A magnetic nanocomposite was synthesized by the hydrothermal approach comprising two building units: metal–organic frameworks (MOFs) and graphene (GR). GR accumulated organic ligands through the large specific surface area and cobalt (Co) and nickel (Ni) served as coordination ions to seamlessly connect with the former for forming CoNi–MOFs–GR (CNMs–GR) to improve the conductivity of MOFs and the electrocatalytic activity of GR. The nanocomposite was utilized to construct an electrochemical sensing platform for the detection of glucose in human blood serum and the removal of organic dyes (methylene blue (MB), congo red (CR), and neutral red (NR)) in water. The CNMs–GR-modified electrode exhibited good electrochemical performance toward glucose in a wide linear range of 10–2900 μM with a detection limit of 1.27 μM. The maximum uptake capacity of CNMs–GR for MB, CR, and NR was 184.29, 912.47, and 894.36 mg/g, respectively. Most obviously, this work provided a strategy for the design of an effective bifunctional nanocomposite, which not only demonstrated the enormous potential for detection of glucose but also realized the removal of organic dyes.

Non-porous covalent organic polymers enable ultrafast removal of cationic dyes via carbonyl/hydroxyl-synergetic electrostatic adsorption

Rapid and highly efficient removal of organic dyes from polluted water is of great significance for environmental protection and water resources management. Herein, an anionic covalent organic polymer (COP), denominated as COPOH+CO, with the fastest cationic dye adsorption kinetics so far was prepared and packed into solid phase extraction cartridges for rapid and automatic water treatment. As-prepared COPOH+CO contains abundant hydroxyl and carbonyl groups. Compared to COPOH and COPCO, other two COPs containing only hydroxyl and carbonyl, respectively, COPOH+CO gives a maximum adsorption capacity of 813 mg·g−1 towards cationic dye methylene blue (MB), which is about 4.6 times the sum of those of COPOH (42.4 mg·g−1) and COPCO (135 mg·g−1), suggesting the existence of 1 + 1 > 2 synergy between carbonyl and hydroxyl groups. Such a synergy is well demonstrated by theoretical calculation, which shows that the mutual penetration distance of electrostatic potentials in MB/COPOH+CO complex (4.722 Å) is much larger than those in MB/COPOH (0.443 Å) and MB/COPCO (1.602 Å). Although the rapid synthesis endows COPOH+CO with very poor porosity, the resulted surface adsorption avoids the long-term mass transfer, thus giving an ultra-fast adsorption kinetics with a so far fastest adsorption rate constant of 0.17 g·mg−1·s−1. This work demonstrates that by using the synergetic effect of surface functional groups, rapidly synthesized non-porous COPs may work as promising adsorbents for fast adsorption of targets.

Adsorption-enhanced catalytic oxidation for long-lasting dynamic degradation of organic dyes by porous manganese-based biopolymeric catalyst

Improving the adsorption kinetics of metal-oxide catalysts is critical for the enhancement of catalytic performance in heterogeneous catalytic oxidation reactions. Herein, based on the biopolymer pomelo peels (PP) and metal-oxide catalyst manganese oxide (MnOx), an adsorption-enhanced catalyst (MnOx-PP) was constructed for catalytic organic dyes oxidative-degradation. MnOx-PP shows excellent methylene blue (MB) and total carbon content (TOC) removal efficiency of 99.5 % and 66.31 % respectively, and keeps the long-lasting stable dynamic degradation efficiency during 72 h based on the self-built continuous single-pass MB purification device. The chemical structure similarity and negative-charge polarity sites of the biopolymer PP improve the adsorption kinetics of organic macromolecule MB, and construct the adsorption-enhanced catalytic oxidation microenvironment. Meanwhile, the adsorption-enhanced catalyst MnOx-PP obtains lower ionization potential and O2 adsorption energy to promote the continuous generation of active substance (O2*, OH*) for the further catalytic oxidation of adsorbed MB molecules. This work explored the adsorption-enhanced catalytic oxidation mechanism for the degradation of organic pollutants, and provided a feasible technical idea for designing adsorption-enhanced catalysts for the long-lasting efficient removal of organic dyes.

Highly efficient removal of organic dyes and heavy metal cation from wastewater by polyphenolate porous coordination polymer

Highly efficient removal of organic dyes and heavy metal cation from wastewater by polyphenolate porous coordination polymer

Crosslinked 3D porous composite foams as adsorbents for efficient organic dye removal

Crosslinked 3D porous composite foams as adsorbents for efficient organic dye removal

3D flower-like CuO@NiAl-LDH microspheres with enhanced removal affinity to organic dyes: mechanistic insights, DFT calculations and toxicity assessment

Highly efficient removal of organic dyes in wastewater is attracting more and more attention.

Visible-light induced photocatalytic removal of methylene blue dye by copper oxide decorated zinc oxide nanorods

The establishment of rod-shaped visible light heterojunction ZnO/CuO composites for potential redox ability presents a potential application prospect in the development of efficient photocatalysts for environmental purification. Herein, the CuO-decorated ZnO nanorods composites with preeminent retrievability were obtained by the simple hydrothermal method. The physicochemical properties of the ZnO, CuO and its composites were explored through systematic characterizations. X-ray diffraction (XRD) results show that the ZnO belongs to the wurtzite structure and CuO belongs to the monoclinic crystal structure. The size, shape and elemental composition of the ZnO/CuO composites were confirmed by high-resolution transmission electron microscopy (HRTEM) and energy dispersive spectroscopy (EDS) analysis. The average length of the nanorods is around 420 to 430 nm and the diameter is around 24–30 nm, respectively. The synthesized CuO/ZnO composites were used as a photocatalyst for the degradation of methylene blue (MB) dye under UV–visible light irradiation (UV–Vis). Particularly, ZnO/CuO (10%) composites achieved 98.5% degradation within 150 min, thus evidence suggesting that ZnO/CuO (10%) composites exhibited the best catalytic activity at optimum photocatalytic conditions. The composite materials contain a synergistic effect/factor, which is positive interaction between the CuO and ZnO to improve the photocatalytic activity. In addition, ZnO/CuO (10%) composites demonstrated good reusability and stability while retaining their high photocatalytic activity. It was estimated that this study could create a new opportunity to fabricate easily recoverable and eco-friendly photocatalysts with nanosized heterojunction for efficient removal of organic dyes, antibiotic pollutants and pesticides etc under visible light irradiation.

Synthesis of novel PANI/PVA-NiCu composite material for efficient removal of organic dyes

The present work aims the synthesis of a novel, low cost, and environmentally friendly PANI/PVA-CuNi composite by chemical oxidative polymerization of aniline monomer and polyvinyl alcohol (PVA) as film matrix; several percentages of copper (Cu) and Nickel (Ni) were used. UV–Visible spectroscopy, FTIR, SEM-EDX, and TGA were used to characterize the nanocomposites. While PANI/PVA-CuNi nanocomposites were investigated in adsorption experiments of methylene blue (MB) under different controlled conditions (time reaction, adsorbent dosage, initial dye concentration, stirring speed, temperature, and pH of the medium) also various kinetic models were employed to evaluate the efficiency of the adsorption. The results revealed that the10 mg of PANI/PVA-Cu50Ni50 and PANI/PVA-Ni composites Catalyst removed (94% and 93% of methylene blue in 180 min respectively at 10−5 M initial concentration of dye, pH of 13, stirring speed of 150 rpm, the temperature of 301 k. the kinetics data were properly fitted with the pseudo second-order model with a correlation coefficient of 0.98262 and 0.95881 using PANI/PVA-Cu50Ni50 and PANI/PVA-Ni, respectively.

Modification of covalent organic framework by hydrolysis for efficient and selective removal of organic dye

The efficient removal of organic dyes from wastewater is still a major challenge, especially for the massive production of dyeing technology. Herein, polyimide-based covalent-organic frameworks (COFs) with a highly ordered conjugated architecture are synthesized through the condensation reaction of pyromellitic dianhydride (PMDA) with tris (4-aminophenyl) amine (TAPA). Due to a repeated cyclic structure, COFs subjected to alkaline hydrolysis can offer a high density of negatively charged carboxylate anions as adsorption sites for cationic methylene blue (MB) dye through electrostatic interactions. The maximum adsorption capacity of MB on hydrolyzed COFs is measured to be 315.6 mg/g at pH = 10 and room temperature. Significantly, hydrolyzed COFs exhibit superior adsorption selectivity for MB in a mixture solution with methyl orange (MO) and rhodamine B (RhB). Overall, hydrolyzed COFs are good candidates to serve as an efficient adsorbent for the removal of MB with a high selectivity in the posttreatment of the dyeing process. The employment of COFs with a highly active surface in this study provides new insights for the future development of efficient adsorbents for organic dyes.

Magnetoconductive poly(3,4-ethylenedioxythiophene)/maghemite adsorbent for the removal of Reactive Black 5 from aqueous media

Efficient removal of organic dyes has attained significant attention for environmental safety concerns. In the current study, the adsorption of toxic anionic dye, Reactive Black 5 (RB), by using magnetoconductive poly(3,4-ethylenedioxythiophene) (PEDOT)/maghemite composite is demonstrated. A simple one step synthesis was adopted to prepare PEDOT/maghemite composites using ammonium persulphate as an oxidant. The morphology of obtained composites confirmed the incorporation of maghemite particles into the PEDOT matrix. The presence of maghemite in the composites was also revealed by XRD analysis. With the increase in maghemite amount, an improvement in the specific surface area and magnetic properties of the composites were observed. Thus, the PEDOT composite with largest wt % of maghemite was selected as an adsorbent for the dye removal from aqueous medium. The removal efficiency of ∼95% was observed for RB dye using PEDOT/maghemite composite. It is one of the earliest reports of PEDOT/maghemite which shows the removal of RB from aqueous medium with promising adsorption behavior. The complete decolorization of dye solution and its easy separation by external magnetic field allow future applications of PEDOT/maghemite in industrial waste water treatment and remediation.

Insights into the Superstable Mineralization of Chromium(III) from Wastewater by CuO.

The removal of CrIII ions from contaminated wastewater is of great urgency from both environmental protection and resource utilization perspectives. Herein, we developed a superstable mineralization method to immobilize Cr3+ ions from wastewater using CuO as a stabilizer, leading to the formation of a CuCr layered double hydroxide (denoted as CuCr-LDH). CuO showed a superior Cr3+ removal performance with a removal efficiency of 97.97% and a maximum adsorption capacity of 207.6 mg/g in a 13000 mg/L Cr3+ ion solution. In situ and ex situ X-ray absorption fine structure characterizations were carried out to elucidate the superstable mineralization mechanism. Two reaction pathways were proposed including coprecipitation-dissolution and topological transformation. The mineralized product of CuCr-LDH can be reused for the efficient removal of organic dyes, and the adsorption capacities were up to 248.0 mg/g for Congo red and 240.1 mg/g for Evans blue, respectively. Moreover, CuCr-LDH exhibited a good performance for photocatalytic CO2 reduction to syngas (H2/CO = 2.66) with evolution rates of 54.03 μmol/g·h for CO and of 143.94 μmol/g·h for H2 under λ > 400 nm, respectively. More encouragingly, the actual tanning leather Cr3+ wastewater treated by CuO showed that Cr3+ can reduce from 3438 to 0.06 mg/L, which was much below discharge standards (1.5 mg/L). This work provides a new approach to the mineralization of Cr3+ ions through the "salt-oxide" route, and the findings reported herein may guide the future design of highly efficient mineralization agents for heavy metals.

Ultrathin WS2 nanobowls-based hybrid aerogels for selective trapping of precious metals from electronic wastes and elimination of organic dyes

Recycling precious metals from electronic wastes, minerals, waste catalysts, industrial wastewater and other wastes are of great significance to the construction of a sustainable industry framework, but it is still challenging. Herein, we for the first time proposed the design and preparation of two three-dimensional (3D) WS2 nanobowls hybrid aerogels (GA@WS2 Nbs and WS2 Nbs/GA) for the recovery of precious metal ions and highly efficient removal of organic dyes. The construction of tungsten disulfide nanobowls (WS2 Nbs) was optimized in morphology in consideration of the precursor concentration and reaction time. The prepared WS2 Nbs/GA was shown to rapidly capture Au(III) from printed wiring board (PWB) containing various interferents. The calculated capture capability of 1265.8 mg g−1 for Au(III) was obtained. It surprisingly involved that the deposition of nano gold (Au0) on the WS2 Nbs/GA was due to not only the selective chemistry of WS2 Nbs/GA but also its reduction interaction. Furthermore, the WS2 Nbs/GA exhibited remarkable efficiencies (99 %) in the removal of methylene blue. The unique properties gave the hybrid aerogels gifted ability in capturing Au(III) from electronic wastes and minerals. It provided a blueprint for the next generation green platform for precious metals and water treatment.

Applications of polyaniline-impregnated silica gel-based nanocomposites in wastewater treatment as an efficient adsorbent of some important organic dyes

AbstractDue to a recent lack of clean water as a result of an increasing water demand, new wastewater solutions are required. Many researchers have looked into the removal of organic dyes from wastewater, with adsorption being an easy and effective method for removing organic and inorganic contaminants from contaminated water. Conjugated modified polymers, primarily polyaniline (Pani), have been widely used in the wastewater treatment because of their unique properties, such as easy synthesis, tunable morphology, porous structure, good electrorheological property, biodegradability, and nontoxic nature. Modified surface polymers are more reactive for the removal of dyes from wastewater and have outstanding dye removal capabilities in the wastewater treatment. This review article elaborates on wastewater treatment by utilizing silica gel-impregnated polyaniline nanocomposites as adsorbents. The use of polyaniline-modified silica gel in dye migration behavior to the most suited system for the resolution of co-existing dyes is referred to as the separation of organic dyes from their mixtures. Adsorption of important organic dyes to optimize conditions for efficient organic dye removal and comparison with another commercially available adsorbent. Chemical modification with the introduction of acidic or basic surface functionality could increase cationic and anionic chemical adsorption, as well as charged organic species such as dyes. The carrier is thus obtained with a chelating reagent on the surface of a silica gel after impregnation with polyaniline.

Efficient removal of organic dyes by Cr-doped ZnO nanoparticles

Efficient removal of organic dyes by Cr-doped ZnO nanoparticles

Facile preparation of floatable carboxymethyl cellulose-based composite hydrogel for efficient removal of organic dyes

Hydrogels have become efficient adsorbents in treatment of organic dyes from wastewater. However, the drawback of difficulty in separation and collection limited their applications. Herein, a series of floatable polyacrylamide/carboxymethyl cellulose‑copper sulfide (PAM/CMC-CuS) hydrogels were designed. The PAM/CMC-CuS hydrogel could not only be easily collected from the wastewater, but also selectively adsorb cationic dyes (Rhodamine B (RhB) and Neutral red (NR)) from the mixed solutions with different oppositely charged dyes. PAM/CMC-CuS hydrogel exhibited faster adsorption rate and higher adsorption capacity than that of PAM/CMC hydrogel. And the adsorption kinetic data were well described by pseudo-second-order model and adsorption isotherm data fitted well with Langmuir equation. Besides, PAM/CMC-CuS hydrogel exhibited excellent reusability and stability that no apparent decrease in removal efficiency was observed after five cycles. Altogether, the good adsorption capacity, floatability, selectivity and reusability will promote the PAM/CMC-CuS hydrogel to be a superior adsorbent in removal cationic dye from wastewater.

Nanolayer-Constructed TiO(OH)2 Microstructures for the Efficiently Selective Removal of Cationic Dyes via an Electrostatic Interaction and Adsorption Mechanism.

Efficient removal of organic dyes from contaminated water has become a great challenge and urgent work due to increasingly serious environmental problems. Here, we have for the first time prepared nanolayer-constructed TiO(OH)2 microstructures which can present negative charge by deprotonation of the hydroxyl group to efficiently and selectively remove cationic dyes from aqueous solution through electrostatic interaction and an attraction mechanism. The nanolayer-constructed TiO(OH)2 microstructures achieve a high adsorption capacity of 257 mg g-1 for methylene blue (MB). The adsorption kinetics, thermodynamics, and isotherms of MB over the TiO(OH)2 microstructures have been studied systemically. The experimental measurements and corresponding analyses demonstrate that the adsorption process of MB on TiO(OH)2 microstructures follows a kinetic model of pseudo-second-order adsorption, agrees well with the Langmuir isotherm mode, and is a spontaneous and exothermic physisorption. Fourier transform infrared (FT-IR) spectra confirm that the prepared TiO(OH)2 microstructures possess hydroxyl group which can deprotonate to present negative charge in solution. Further experimental studies evidently demonstrate that the TiO(OH)2 microstructures also can remove other cationic dyes with positive charge such as basic yellow 1, basic green 4, and crystal violet but cannot adsorb anionic dye of methyl orange (MO) with negative charge in aqueous solution. The measurements for FT-IR spectra and the adsorption of cationic and anionic dyes evidently reveal that the adsorption of cationic dyes over the TiO(OH)2 microstructures is achieved by the electrostatic interaction and attraction between TiO(OH)2 and the dye. This work opens a strategy for the design of new absorbents to efficiently remove organic dyes from aqueous solution through an electrostatic attraction-driven adsorption process.

Graphene Oxide-Chitosan Network on a Dialysis Cellulose Membrane for Efficient Removal of Organic Dyes.

Currently, water pollution is a significant health problem for both humans and animals due to large amounts of dye-containing wastewater. Thus, polymer composite membranes (PCMs) are considered as efficient adsorption/filtration membranes that can be utilized for removing organic dyes from contaminated water/wastewater. In this study, the goal is to explore the modification of the interfacial dialysis cellulose (DC) surface through molecular interactions of an active graphene oxide-chitosan (GO-CTS) composite hydrogel (GCCH) network without the use of an external cross-linker toward an effective dye removal ability using a simple casting process and a low-cost adsorption technique, resulting in the formation of a PCM, i.e., GO/CTS/DC membrane (GCD-mems). Concomitantly, the incorporation of the GCCH network (as an active hybrid network) and DC (as a supporting material) is considered as a promising approach toward a dye-removing PCM. As a result, the GCD-mems showed that cellulose robustly interacted via the chemical bonds of the GCCH network by maintaining the three-dimensional (3D) porous layer structures, and the functional surface of the membrane was enhanced toward specific groups for an effective dye removal approach. In addition, there is a significant improvement in dye removal performance after modification of the interfacial DC surface through molecular interactions of GCCH, i.e., high adsorption capacities of cationic and anionic dye molecules on the GCD-mems, compared to the relevant GO-based adsorbents. Also, the dye flux and rejection of the GCD-mems can simultaneously remove both methylene blue and Congo red. In the adsorption, it is appropriate with the pseudo-second-order and Langmuir models corresponding to chemical adsorption and monolayer approaches, as well as physical sieving through the 3D layers of porous channels of GCD-mems during the filtration process. Moreover, the structural stability and sustainability of the PCMs are enhanced during the recycling process, and the use of ethanol in the recycling process further simplifies the process and reduces the cost of the PCMs. Thus, the GCD-mems are encouraged as potential candidates that can be applied directly in the removal of dyes from the wastewater of textile industries or selective dialysis applications.

Electroactive adsorbent composites of porous graphite carbon/carbon nanotube for highly efficient organic dye removal

Electroactive adsorbent composites of porous graphite carbon/carbon nanotube for highly efficient organic dye removal